Energy-saving production process method for rapid drying and dewatering of paper-plastic products

ABSTRACT

An energy-saving production process method for rapid drying and dewatering of paper-plastic products, which is applied to production of paper-plastic products, and mainly comprises a cold extrusion press station ( 2 ) which is independent and is arranged between a pulp suction forming station ( 1 ) and a hot-press shaping station ( 3 ); the cold extrusion press station ( 2 ) is provided with a top mold and a lower mold ( 21, 22 ) which can form a mold closing mold closing gap according to the shape and size of a product, the mold closing mold closing gap is used to first press a primary product to discharge water of about 30% to 50%, and then send same to the hot-press shaping station for continuous dewatering to below 3% to form a paper-plastic product. The paper-plastic product produced by using the present production process can shorten the production time and reduce the consumption of heat energy for drying.

TECHNICAL FIELD

The present invention relates to an energy-saving production process method for rapid drying and dewatering of paper-plastic products.

BACKGROUND

With the deepening and demand for environmental protection, the technical improvement of the production process of degradable and recycled products is becoming more and more important, especially for the paper-plastic products made of herbal plant fibers are non-toxic and degradable. Characteristics of recyclability and remanufacturing have become the vanguard of environmentally friendly products, and the production process of paper-plastic products contains: a pulp suction forming, a hot-press shaping station, and a cutting station. How to reduce heat energy consumption and reduce the time for hot-press shaping in a technical field is a big issue for technicians. A conventional pulp suction process uses the vacuum suction technology to form a blank. The water content of the blank is about 70%-80%, and then the blank is dried by various heating and dewatering. However, in the process of using thermal power to directly reduce the water content of the blank to below 3%, a loss of heat energy is quite huge, and it takes a lot of time, thus increasing production cost.

Another conventional production process method for drying and dewatering of paper-plastic products contains steps of: a pulp suction forming, a cold-press shaping, a hot-press shaping, and a cutting. In the step of pulp suction forming, a cold-press mold is connected with a pulp sucking mold so as to press and discharge water from the blank, thus reducing a water content of the blank from 70 to 80% to 50 to 60% to produce wet blank. The wet blank is delivered to the hot-press shaping station to de dewatered below 3% water content, thus producing a semi-finished product. When dewatering the semi-finished product in the cold-press shaping station, as shown in FIGS. 4 to 6 , a pulp sucking mold 91 includes an air mesh 93 configured to filter and suck paper pulp, and the air mesh 93 has multiple air-permeable sheets 93 connected on the air mesh 93, as illustrated in FIG. 6 , wherein multiple bores 930 are formed on a respective one air-permeable sheet 93. When pressing the semi-wet blank M by using a press mold 92, the multiple bores 930 of the respective one air-permeable sheet 93 of the pulp sucking mold 91 are adhered, as shown in FIG. 5 , thus only demolding the semi-wet blank M with a large slope. In other words, the semi-wet blank M with a small slop or an angle will be scratched by the respective one air-permeable sheet 93 to damage the paper pulp or block the paper pulp in the multiple bores 930. Also, a demolding slope of the cold-press mold and the pulp sucking mold will limit shapes and angle of the paper-plastic product.

Furthermore, when pressing the blank to the pulp sucking mold 91 by using the press mold 92, a mold closing gap between the press mold 92 and the pulp sucking mold 91 is not calculated to cause a thicker or thinner thickness of the semi-wet blank M, thus having defective rate to the paper-plastic products. When the thickness of the semi-wet blank M is thick, the paper-plastic products will produce macula. When the thickness of the semi-wet blank M is thin, a durability, a flexibility and a strengthens of the paper-plastic products are decreased to cause uneven patters of the paper-plastic products. Also, a high production cost will occur.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.

SUMMARY

The primary aspect of the present invention is to provide an energy-saving production process method for rapid drying and dewatering of paper-plastic products.

To obtain above-mentioned aspect, an energy-saving production process method for rapid drying and dewatering of paper-plastic products provided by the present invention contains: providing a top mold and a lower mold to cold extrusion press a blank in a cold extrusion press station, wherein the cold extrusion press station is arranged between a pulp suction forming station and a hot-press shaping station, such that a step of vacuum pulp-suction dewatering, a step of cold extrusion dewatering, and a step of hot-press dry dewatering are executed in turns.

In the cold extrusion press station, a mold closing gap is formed after the top mold and the lower mold are connected, and the top mold and the lower mold are configured to press the blank;

In the hot-press shaping station, a mold closing gap between the top mold and the lower mold is equal to a thickness of a finished product, and a thickness of a semi-finished product after being dried in the hot-press shaping station is equal to the thickness of the finished product;

In the cold extrusion press station, a mold closing gap between the top mold and the lower mold is 1 to 1.3 times more than the thickness of the finished product, and a thickness of a semi-dried blank pressed in the cold extrusion press station is 1 to 1.3 times more than the thickness of the finished product.

In the pulp suction forming station, a mold closing gap between the top mold and the lower mold is 2 to 2.3 times more than the thickness of the finished product, and a thickness of the blank in the pulp suction forming station is 2 to 2.3 times more than the thickness of the finished product.

Preferably, the energy-saving production process method as claimed in claim 1, wherein the lower mold includes a vacuum cavity formed on a bottom thereof, an accommodation chamber defined above the vacuum cavity and configured to accommodate the blank, a molding face formed on the accommodation chamber and corresponding to a shape of the blank, and multiple air orifices defined between and passing through the vacuum cavity and the accommodation chamber so as to vacuum and suck waters of the blank or the semi-dried in the pulp suction forming station, the cold extrusion press station and the hot-press shaping station in a negative pressure.

Preferably, the lower mold includes an air mesh fixed on a portion of the lower mold which is demolded over 5 degrees, and the other portion of the lower mold demolded less than degrees does not have the air mesh.

Preferably, a pulp material is feed and sucked in the pulp suction forming station to form the blank, and the blank is delivered into the accommodation chamber of the lower mold in the cold extrusion press station and is extrusion pressed by the top mold and the lower mold, wherein the blank is extrusion pressed by the top mold and is negative-pressure vacuumed to contact with the molding face of the lower mold and the air mesh matingly, such that the blank is further extrusion pressed in the cold extrusion press station to discharge water, then the water of the blank is negative-pressure vacuumed to attach on the vacuum cavity via the multiple air orifices and then to be discharged out of the lower mold, hence the water content of the blank A is reduced to 55% to 60% from 68% to 75%, thus producing the semi-dried blank B with a water content below 3%.

Preferably, a ratio of drying times in the cold extrusion press station and the hot-press shaping station is 1:2, and a ratio of an energy consumption in the cold extrusion press station and the hot-press shaping station is 2:3.

Thereby, the energy-saving production process method of the present invention contains the vacuum pulp-suction dewatering, the cold extrusion dewatering, and the hot-press dry dewatering, wherein the vacuum pulp-suction dewatering is configured to reduce the water content of the blank A to 68% to 75%, the cold extrusion dewatering is applied to dewatered the blank A to produce the semi-dried blank B with 50% to 60% water content, and the hot-press drying dewatering is used to dewater the semi-dried blank B with the 50% to 60% water content to produce the semi-finished product C with below 3% water content, thus shortening a production time and reducing a consumption of heat energy for drying.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the flow chart and a change of water content and a thickness of a blank produced by an energy-saving production process method for rapid drying and dewatering of paper-plastic products according to a preferred embodiment of the present invention.

FIG. 2 is a cross sectional view showing the operation of the energy-saving production process method for rapid drying and dewatering of the paper-plastic products according to the preferred embodiment of the present invention.

FIG. 3 is a cross sectional view showing the assembly of a lower mold in a cold extrusion press station according to the preferred embodiment of the present invention.

FIG. 4 is a cross sectional view showing the operation of a conventional cold extrusion press mold and a conventional pulp suction mold.

FIG. 5 is a cross sectional view showing the assembly of a blank and a conventional air mesh in a conventional cold extrusion press station.

FIG. 6 is a perspective view of a conventional air mesh.

DETAILED DESCRIPTION

With reference to FIGS. 1-3 , an energy-saving production process method for rapid drying and dewatering of paper-plastic products according to a preferred embodiment of the present invention comprises a step of providing a top mold 21 and a lower mold 22 to cold extrusion press a blank A in a cold extrusion press station 2 according to a shape and a size of a product, wherein the cold extrusion press station 2 is independent and is arranged between a pulp suction forming station 1 and a hot-press shaping station 3, such that a step of vacuum pulp-suction dewatering, a step of cold extrusion dewatering, and a step of hot-press dry dewatering are executed in turns, wherein in the cold extrusion press station 2, a mold closing gap 225 is formed after the top mold 21 and the lower mold 22 are connected, and the top mold 21 and the lower mold 22 are configured to press the blank A. In the hot-press shaping station 3, a mold closing gap between the top mold 21 and the lower mold 22 is equal to a thickness X of a finished product, and a thickness C of a semi-finished product C after being dried in the hot-press shaping station 3 is equal to the thickness X of the finished product. In the cold extrusion press station 2, a mold closing gap between the top mold 21 and the lower mold 22 is 1 to 1.3 times more than the thickness X of the finished product, and a thickness of a semi-dried blank B pressed in the cold extrusion press station 2 is 1 to 1.3 times more than the thickness X of the finished product. In the pulp suction forming station 1, a mold closing gap between the top mold 21 and the lower mold 22 is 2 to 2.3 times more than the thickness X of the finished product. In other words, a thickness of the blank A in the pulp suction forming station 1 is 2 to 2.3 times more than the thickness X of the finished product. The lower mold 22 includes a vacuum cavity 223 formed on a bottom thereof, an accommodation chamber 221 defined above the vacuum cavity 223 and configured to accommodate the blank A, a molding face 222 formed on the accommodation chamber 221 and corresponding to a shape of the blank A, and multiple air orifices 224 defined between and passing through the vacuum cavity 223 and the accommodation chamber 221 so as to vacuum and suck waters of the blank A or the semi-dried blank B in the pulp suction forming station 1, the cold extrusion press station 2 and the hot-press shaping station 3 in a negative pressure. To shape different surfaces of the paper-plastic products at different angles, the lower mold 22 includes an air mesh 4 fixed on a portion of the lower mold 22 which is demolded over 5 degrees, and the other portion of the lower mold 22 demolded less than 5 degrees does not have the air mesh 4 but has the multiple air orifices 224 passing through and between the other portion of the lower mold 22 and the vacuum cavity 223.

Technicians who are familiar with the paper-plastic product industry know that based on a vacuum pulp-suction dewatering, when a cost of the vacuum pulp-suction dewatering is 1, a ratio of costs of the vacuum pulp-suction dewatering, the cold extrusion dewatering and the hot-press dry dewatering is 1:70:330. Under a same amount of dewatering, a reduced cost of the cold extrusion dewatering is 70 times more than the vacuum pulp-suction dewatering, and a reduced cost of the hot-press dry dewatering is about 5 times more than the cold extrusion dewatering. The vacuum pulp-suction dewatering is merely configured to suck free water on the blank A, thus having a limited dewatering effect. In other words, the free water of the blank A is dewatered at 10% to 15% in the step of the vacuum pulp-suction dewatering. The thickness of the blank A is thinned in the step of the cold extrusion dewatering to discharge the free water from the blank A, wherein discharge ratios of the paper-plastic products of different thicknesses and shapes are different and are within a 30% to 50% water content of the blank A. However, only the free water of the blank A is discharged in the steps of the cold extrusion dewatering, but a connected water is not discharge from the blank A. In the step of the hot-press dry dewatering, the free water and the connected water of the semi-dried blank B are discharged by vaporizing, thus reducing the water content of the semi-dried blank B below 3%. A dewatering time in the step of the hot-press dry dewatering is changeable based on the different sizes, shapes and thicknesses of the paper-plastic products, wherein the lower the water content of the blank A is, the shorter the dewatering time of the step of the hot-press dry dewatering is, and a relative heat energy consumption is also reduced.

In this embodiment, the cold extrusion press station 2 is arranged between the pulp suction forming station 1 and the hot-press shaping station 3, wherein a pulp material is feed and sucked in the pulp suction forming station 1 to form the blank A, and the blank A is delivered into the accommodation chamber 221 of the lower mold 22 in the cold extrusion press station 2 and is extrusion pressed by the top mold 21 and the lower mold 22, wherein the blank A is extrusion pressed by the top mold 21 and is negative-pressure vacuumed to contact with the molding face 222 of the lower mold 22 and the air mesh 4 matingly, such that the thickness of the blank A is 2× to 2.3× in the pulp suction forming station 1, and the blank A is further extrusion pressed in the cold extrusion press station 2 to reduce the thickness of the blank A to 1× to 1.3× and to discharge water, then the water of the blank A is negative-pressure vacuumed to attach on the vacuum cavity 223 via the multiple air orifices 224 and then to be discharged out of the lower mold 22, hence the water content of the blank A is reduced to 50% to 60% from 68% to 75%, thus producing the semi-dried blank B at a lower water content. Thereafter, the semi-dried blank B is carried to the hot-press shaping station 3 so as to be pressurized and heated, such that the free water and the connected water of the semi-dried blank B are discharged by vaporizing, and a water content of the semi-dried blank B is reduced below 3% from 55% to 60% to produce the semi-finished product C. Since the extrusion pressing and the negative-pressure vacuuming are well-known prior art, further remarks are omitted.

In below testing process, when the blank A with 72.8% water content is directly delivered to the hot-press shaping station 3 for drying without being delivered to the cold extrusion press station 2, a semi-finished product C with 1.4% water content is produced, wherein a drying time of the blank A with 72.8% water content is 29 seconds. When the blank A with 72.8% water content is delivered to the cold extrusion press station 2 to be extrusion pressed for 10 seconds, a semi-dried blank B with a reduced 33.3% water content is produced, then the semi-dried blank B with the reduced 33.3% water content is moved to the hot-press shaping station 3 to be hot-press dried for 15 seconds, thus producing a semi-finished product C with 1.4% water content. Thereby, the blank A with 72.8% water content is dried to produce the semi-finished product C with the 1.4% water content. It is to be noted that when the blank A with the 72.8% water content is directly delivered to the hot-press shaping station 3 for drying without being delivered to the cold extrusion press station 2, the drying time of the blank A with the 72.8% water content is 29 seconds. However, when the blank A with the 72.8% water content is delivered to the cold extrusion press station 2 to be extrusion pressed, and the semi-dried blank B with the reduced 33.3% water content is produced and is moved further to the hot-press shaping station 3 to be hot-press dried for 15 seconds, wherein a ratio of drying times of the above-mentioned two methods is 2:1. The semi-dried blank B with the reduced 33.3% water content in the cold extrusion press station 2 is saved heat energy of the hot-press shaping station 3, wherein a ratio of the saved heat energy of above-mentioned two stations is 3:2. But, under different factors (such as a mold shape, product shape, size and thickness, the ratios of the drying time) are different. Preferably, when the blank A is extrusion pressed in the cold extrusion press 2 and then is dried in the hot-press shaping station 3 to produce the semi-finished product C, the drying time is shorter and a heat consumption is decreased.

From above-mentioned testing result, the drying times to the semi-dried blank B and the blank A with the 1.4% water content are 15 seconds and 29 seconds respectively, thus saving 14-seconds energy consumption and drying time. When the blank A with more water content is hot-press dried in the hot-press shaping station 3, the lower mold 22 is cooled by the water and is vaporized effectively, so a heating temperature has to be compensated, and more water content is vaporized, thus increasing the drying time. A cooling effect of the lower mold in the hot-press shaping station 3 is lower than that of the semi-dried blank B in the cold extrusion press station, thus a temperature compensating speed and a vaporizing speed of the lower mold in the hot-press shaping station is faster.

Thereby, the energy-saving production process method of the present invention comprises the steps of the vacuum pulp-suction dewatering, the cold extrusion dewatering, and the hot-press dry dewatering, wherein the vacuum pulp-suction dewatering is configured to reduce the water content of the blank A to 68% to 75%, the cold extrusion dewatering is applied to dewatered the blank A to produce the semi-dried blank B with 55% to 60% water content, and the hot-press drying dewatering is used to dewater the semi-dried blank B with the 50% to 60% water content to produce the semi-finished product C with below 3% water content, thus shortening a production time and reducing a consumption of heat energy for drying.

While the first embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. The scope of the claims should not be limited by the first embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. 

What is claimed is:
 1. An energy-saving production process method for rapid drying and dewatering of paper-plastic products comprises steps of: providing a top mold and a lower mold to cold extrusion press a blank in a cold extrusion press station, wherein the cold extrusion press station is arranged between a pulp suction forming station and a hot-press shaping station, such that a step of vacuum pulp-suction dewatering, a step of cold extrusion dewatering, and a step of hot-press dry dewatering are executed in turns; wherein in the cold extrusion press station, a mold closing gap is formed after the top mold and the lower mold are connected, and the top mold and the lower mold are configured to press the blank; wherein in the hot-press shaping station, a mold closing gap between the top mold and the lower mold is equal to a thickness of a finished product, and a thickness of a semi-finished product after being dried in the hot-press shaping station is equal to the thickness of the finished product; wherein in the cold extrusion press station, a mold closing gap between the top mold and the lower mold is 1 to 1.3 times more than the thickness of the finished product, and a thickness of a semi-dried blank pressed in the cold extrusion press station is 1 to 1.3 times more than the thickness of the finished product; and wherein in the pulp suction forming station, a mold closing gap between the top mold and the lower mold is 2 to 2.3 times more than the thickness of the finished product, and a thickness of the blank in the pulp suction forming station is 2 to 2.3 times more than the thickness of the finished product.
 2. The energy-saving production process method as claimed in claim 1, wherein the lower mold includes a vacuum cavity formed on a bottom thereof, an accommodation chamber defined above the vacuum cavity and configured to accommodate the blank, a molding face formed on the accommodation chamber and corresponding to a shape of the blank, and multiple air orifices defined between and passing through the vacuum cavity and the accommodation chamber so as to vacuum and suck waters of the blank or the semi-dried in the pulp suction forming station, the cold extrusion press station and the hot-press shaping station in a negative pressure.
 3. The energy-saving production process method as claimed in claim 2, wherein the lower mold includes an air mesh fixed on a portion of the lower mold which is demolded over 5 degrees, and the other portion of the lower mold demolded less than degrees does not have the air mesh.
 4. The energy-saving production process method as claimed in claim 3, wherein a pulp material is feed and sucked in the pulp suction forming station to form the blank, and the blank is delivered into the accommodation chamber of the lower mold in the cold extrusion press station and is extrusion pressed by the top mold and the lower mold, wherein the blank is extrusion pressed by the top mold and is negative-pressure vacuumed to contact with the molding face of the lower mold and the air mesh matingly, such that the blank is further extrusion pressed in the cold extrusion press station to discharge water, then the water of the blank is negative-pressure vacuumed to attach on the vacuum cavity via the multiple air orifices and then to be discharged out of the lower mold, hence the water content of the blank A is reduced to 55% to 60% from 68% to 75%, thus producing the semi-dried blank B with a water content below 3%.
 5. The energy-saving production process method as claimed in claim 1, wherein a ratio of drying times in the cold extrusion press station and the hot-press shaping station is 1:2, and a ratio of an energy consumption in the cold extrusion press station and the hot-press shaping station is 2:3. 